Unless the bad guys have the keys used to authenticate updates, you are OK. If the bad guys can break or cajole Microsoft, you are likely already compromised.
The situation gets weird when the bad guys are able to track Microsoft's critical patches, and reverse-engineer them.
There is one attack vector that may be used: blocking access to Windows Update servers while exploiting the remote vulnerability that the updates were supposed to patch.
After they install the rootkit on your machine, the patch may be allowed to proceed. This method relies on high numbers of compromised routers and rather sophisticated attackers who aren't content with password phishing.
To answer your question directly: being abroad does increase the risk, since you are by definition visiting many places where you haven't been before. Hotel chains are known to be compromised.